1. Field of the Invention
The present invention relates generally to the execution of application programs on hand-held digital wireless data communication and computing devices of the types generally referred to as hand-held computers, personal digital assistants, cellular telephones, pagers and the like.
2. Description of the Related Art
A distinct category of electronic communication and computing devices increasingly referred to in the art simply as “wireless devices” is coalescing from the previously distinct fields of mobile computing and cellular telephony. The category includes devices commonly referred to as palmtop or hand-held computers, personal digital assistants, organizers, “smart” cellular telephones, pagers, and the like. Cellular and similar mobile telephones and telephone-like devices include computer application program-like functions, such as games, contact managers and e-mail. Personal digital assistants (PDAs) and other computer-like devices can include remote communication functions such as wireless networking for communicating e-mail and data. The convergence of wireless digital communication and mobile computing has given rise to wireless devices with substantial application program-like functionality.
There are presently few standards for wireless devices in the areas of operating systems and user interfaces. The operating systems of most wireless devices are proprietary to their manufacturers and thus not used in wireless devices produced by other manufacturers. Some wireless devices have user interfaces based upon a touch-screen display with which one can interact using a stylus or finger, while others have actual buttons a user can depress, and still others have a miniature alphanumeric keyboard on which a user can type. Wireless devices having various combinations of touch-screens and buttons are known. Display size and shape varies considerably among wireless devices. Of those having buttons, the style, placement and number of buttons varies considerably. In some devices, one uses directional buttons or joystick-like pucks to navigate among menu options or move a cursor on the screen, while in others one uses the touch-screen to perform such functions. Also, the mechanisms that wireless devices use to store and retrieve data in memory vary considerably. The differences among platforms are expected to increase, as new technologies emerge for user interfaces, data storage, communication and other functions. For example, wireless devices and similar platforms having a voice-based user interface instead of buttons and touch-screens have been suggested.
Differences among wireless device platforms (the term “platform” referring to the environment defined by the device hardware in conjunction with its operating system software) have frustrated third-party software developers' efforts to create application programs that are executable on more than one platform. To be executable on a specific platform, the program must properly interface with the buttons or other user interface inputs and the screen or other user interface outputs. For example, the application program must take into account the size and shape of the screen to ensure that information written to the screen appears in the intended position and format. Similarly, the program must properly interface with whatever mechanism the platform uses to store and retrieve information in memory and whatever mechanism the platform uses for network communication. An application program such as an e-mail client that is written to be executable on one platform will generally not be executable on another platform. Thus, if a software developer wishes to market an e-mail client application program, a different version must be written for each platform to whose users the developer wishes to market the program.
The advent of the JAVA language, promulgated by Sun Microsystems, Inc., has brought some limited uniformity to wireless devices. As illustrated in FIG. 1, a JAVA application program 12 can be written to execute on a wireless device having a JAVA virtual machine (JVM) software layer 14. JVM layer 14 resides on top of whatever native operating system software and hardware combination 16 characterizes the platform. Including JVM layer 14 that can execute JAVA application 12 can obviate writing a native application 18 that more directly executes on native operating system software and hardware combination 16. The difficulty of this approach to achieving cross-platform application program compatibility is that JVM layer 14 may not be the same across all platforms. The limitations on memory and power in wireless devices generally prevents including a full Java Virtual Machine implementation. Consequently, JVM layer 14 in some wireless devices may represent a more complete implementation of Sun Microsystems' JVM standard than in others. An application programmer cannot be certain that an application program written to take advantage of specific JAVA features will run on all platforms having JVM layer 14 because some platforms may support that feature and others may not. In an effort to remedy this problem, an industry standards committee developed the Connected Limited Device Configuration (CLDC) and Mobile Information Device Profile (MIDP) specifications. Including CLDC and MIDP layers 20 provides a limited but standardized JAVA environment for which programmers can write applications 22 that will work on all such devices.
Another limitation of wireless devices is that their operating systems do not provide mechanisms for readily switching from one application program to another or allowing application programs to share components. Wireless device application programs are generally self-contained in the sense that they do not share components. Operating systems for personal computers, such as MICROSOFT WINDOWS, include sophisticated methods such as the dynamically linked library (DLL) for juggling application programs, sharing software components, and similar interrelated operating system tasks, but the memory and power limitations of wireless devices generally inhibit use of such methods. Thus, wireless devices typically use the simplest of methods for launching and controlling the execution of programs. For example, activating a button (either an actual pushbutton or a graphical button appearing on a display) may cause a program to begin executing. The program may present output to the user in the form of screen displays and receive input from the user in the form of button activations. When the program has finished executing or at such other time as the user desires, the user can lauch and interact with another program in the same manner. Each program is, in essence, a self-contained block of software code, and only one program is executable at a time.
A user is not only limited as described above in the ways in which programs in a wireless device can be switched between, started and stopped, but a user is similarly limited in the ways in which programs can be installed, un-installed, updated, initialized and similarly managed in a wireless device. For example, a user can typically install new application programs only by connecting the wireless device to a network server or a personal computer through a network connection or other interface. It is common to download programs from an Internet server. In the case of most wireless devices, the user must perform the steps necessary to effect the download, installation, initialization or other task. In at least one case, a mobile telephone, a remote entity can initiate limited tasks such as enabling or disabling an application in the phone.
It would be desirable to free wireless device users from application management tasks such as installing, un-installing, initializing, enabling and disabling. The present invention addresses these problems and deficiencies and others in the manner described below.